An alternative model for analysis of the instability of the stiffeners in the process of manufacturing reinforced PVC pipes

Reinforced PVC pipes are being used as underground conduit for liquids flowing in open-channel conditions as an alternative to the cast iron or cement pipes. The reinforced pipes are obtained by rolling up a PVC ribbed blade. The product is a low-weight pipe, with adequate stiffness and resistance. A critical disadvantage is that sometimes during the process of rolling up the pipe, there is instability in the ribbings of the profile. This instability makes the formed pipe useless, since it will not have either the desired stiffness or resistance. This problem was previously addressed using the theory of buckling of beams of open section and thin walls, under bending. In this work, a new model is presented, based on the compression of a plate, as an alternative model, preventing some disadvantages of the model based on the theory of buckling of beams. The proposed model can advantageously replace the models based on the buckling theory for thin-walled open cross-section beams.